1. Technical Field
The present invention relates, in general, to a linear vibrator.
2. Description of the Related Art
Generally, a diversity of vibrators are provided in mobile electronic appliances, such as mobile phones, gaming machines, portable information terminals or the like, in order to, for example, provide a muting function and to prevent noise from creating disturbances in public places. In particular, such a vibrator is mounted in a portable phone to render an incoming call signal mute. Because of the recent tendency to make a portable phone having a small and slim size, the vibrator mounted in such a portable phone is also needed to be made small and slim in size as well as to have a high number of functions.
A vibrator is one of the call-receiving units which is presently being adapted to communication appliances such as portable phones. It is an element which converts electric energy into mechanical vibrations using the principle of creating an electromagnetic force, and is mounted in a portable phone for informing the owner of the phone of an incoming call in a mute state.
A conventional vibrator according to an embodiment of the prior art obtains mechanical vibrations by rotating a rotor having an eccentric weight. The rotating force of the rotor is obtained by a commutator or brush type motor structure, wherein an electric current is supplied to a coil of the rotor after being commutated via a contact between a brush and a commutator.
However, such a vibrator has a problem in that, when the brush passes through a gap between segments of the commutator, mechanical friction, electric sparks and abrasion occur there, and thus foreign material such as a black powder is created which shortens the lifetime of the vibrator. Therefore, a linear vibrator which is capable of stably obtaining to linear vibrations was proposed.
FIG. 1 is a cross-sectional view illustrating a conventional linear vibrator.
As illustrated in FIG. 1, the conventional linear vibrator 10 includes a casing 20 defining an internal space of the vibrator, a bracket 30 disposed under the casing 20 and having a coil 32, to which electricity is applied to induce a magnetic field, and a damper member 34, an oscillator 40 having a hollow yoke 42, a cylindrical magnet 44 received in the hollow portion of the yoke with a plate yoke 43 attached onto the lower surface thereof, and a weight 46 coupled onto the circumference of the yoke 42, and a spring member 50 coupled with an upper portion of the casing 20 to elastically support the oscillator 40 such that the oscillator 40 can move in a linear motion. Here, the hollow yoke 42 is a cylindrical element, one end of which is closed, and consists of a disk plate 42a and a cylindrical wall portion 42b extending downwards from the circumference of the disk plate 42a. 
The linear vibrator 10 is operated such that, when electricity is supplied to the coil 32, the oscillator 40 begins to vibrate in a vertical direction owing to interaction between the magnetic field, which is created from a magnetic circuit composed of the cylindrical magnet 44, the plate yoke 43, and the yoke 42 and an electric field which is created from the coil 32.
However, such a conventional vibrator 10 has a problem in that, when external force is applied to the oscillator 40 in an inactivated state, because the oscillator 40 is connected with the spring member 50, unavoidable slight vibrations are generated to the oscillator 40, reducing reliability of the vibrator 10.
Further, when the oscillator 40 moves in a lateral motion or a rotating motion in an activated state, the oscillator 40 comes into direct contact with the casing 20, problematically creating touch sounds and impact.